In 2005 and this year there have been several discussions on wetpixel about seeing warmer water species moving up North to beat the heat. CNN has a report on a comprehensive review looking at migration, adaptation, and extinction of species (not only fish). The conclusion is that nature's reaction to global warming is not something of the future but is already going on, and heat sensitive animals and plants that can't move towards the poles are in decline or already extinct.
Bart
